A 3D carousel data visualization is inspired by a table with a rotatable carousel in our daily life. By rotating the carousel on the table as shown in FIG. 1, all dishes laid on the table will be presented before diners. Like to this, the 3D carousel data visualization presents a plurality of data nodes (such as files, folders, etc.) on a 3D carousel, and a user can select nodes of interest one by one through rotating the carousel. Such a man-machine interface is not only a straight, inviting and aesthetical layout, which facilitates the understanding of users, but also focuses the front position to be larger and more eye-catching than focuses in the rear due to the utilization of 3D visual experience. It arouses more users' attention. Additionally, such animated rotation provides an interesting use experience for users because of added interactions with users.
Currently, applications of such 3D carousel data visualization and variations of the visualization of tree data structures are prevalent in the field of computer applications. For example, the paper entitled “Designing a Generalized 3D Carousel View,” under the subtitle Late Breaking Results: Short Papers and published by Shuo Wang et al. in 2005, pages 2017-2020 discloses a method of carousel data visualization. In this method, each file is shown around the outline of the carousel as an icon. When a user drags the carousel, finds a focus file, and clicks an icon corresponding to the file, the carousel will be smoothly rotated to the target the user desires, i.e. the focus is found. In this manner, users can easily select a file. FIG. 2 shows a prototype of carousel visualization obtained using the aforesaid method of data visualization. The “Termination Marker” is to determine a market point during rotation and thereby make a user aware of whether the carousel has been rotated for a whole round, i.e. to mark that the user has searched all over from this node (icon). In the “Clipping Area” are placed other icons that cannot be visualized completely. The numeral 36 denotes that in the “Clipping Area” are placed the icons of 36 files. The carousel generated according to the method of “focus+context effect” as described in the paper is clearly shown in FIG. 2. The front icons are larger than the icons in the back, which is a natural result generated by applying 3D visual experience to the carousel visualization.
The visualization method described in the paper and many other applications of 3D carousel visualization, such as computer games, media explorers have testified that 3D carousel visualization is very suitable for presenting icons, pictures or any other items that can be represented by images. However, it is not a good choice to visualize an item list with long text strings with 3D carousel visualization.
The 3D carousel visualization method is also adopted by a variety of well-known visualization method, such as a method of layout out 3D hierarchical structures and a corresponding interaction manner, described by Robertson G. McKinley J D, et al. in the paper “Cone Trees: Animated 3D Visualizations of Hierarchical Information” published in Proceedings of the ACM Human Factors in Computing Systems (CHI'91), 1991. It is clear from this paper, with respect to a limited visualization interface such as a display screen of a certain size, and when there is a relatively large number of nodes, the respective node of a cone tree will be superposed with one other so that data information cannot be presented effectively. Accordingly, the cone-tree visualization method is not suitable to a solution with a large data set. The EP 0435601 B1 also discloses a visualization method of presenting hierarchical structures in a 3D space in the manner of nodes and links. In this method, all nodes are laid out in a 3D space at a time. Like the cone-tree visualization method, in the case that where there is a relatively large number of nodes, respective nodes will be superposed one another. Additionally, in these two visualization methods, upon the receipt of an instruction indicating that the user has selected a node of interest, the selected node will become the current focus through rotation, while each branch in the previously-visualized tree structure will be kept. Hence, all branches in the previously-visualized tree structure also will be kept even if they have little relevance to the currently-selected focus. Then since the number of such branches grows and nodes involved increase, focuses will be pushed to a side for visualization, so the utility of the visualization interface is reduced dramatically.
EP 0694878A2 also discloses a method of incrementally laying out a tree structure on a plane. In this method, nodes of each hierarchy in the tree structure are statically laid out on a plane, and the focus of a view cannot be changed or highlighted. As a result, it is difficult for uses to learn about the context of the focus in the miscellaneous overall layout. This method also contains the above-mentioned problems, such as node superposition and low utility of the visualization interface.
Although 3D carousel user interfaces are employed by more and more application as described previously, none of the above applications can efficiently handle the visualization of hierarchically-structured data of a huge amount. Nor could it propose any optimizations to the interaction mechanism of the visualization of a 3D hierarchical structure. Therefore, there is a need for a visualization method and device capable of highlighting focuses of interest to users in a tree hierarchical data and utilizing a visualized interface more efficiently.